Part 54

Right near the place where the pipe goes in is a stairway which leads up to the top of the wall, so the whole crowd of boys and girls climb the steps and you are at the top of the reservoir; and there spread out before you, you see a big lake surrounded with a stone wall and you see where the water comes from--the reservoir--at least so you think. But you are wrong. You really haven’t come anywhere near the source of the supply. For soon as you walk around the broad top of the wall which surrounds your reservoir, you meet a man who asks you what you want, and you tell him that you have been finding out where the water in the faucet came from, but having found out you thought you would go back home.

The man smiles at you, but, as he is good-natured and sees you are really trying to find out where the water comes from, he tells you that since you have gone to all the trouble of digging up the streets to follow the pipes, you might as well learn all about it.

He first tells you that the reservoir is not really the place where the water comes from but only a tank, so to speak. He explains to you that most of the faucets in the city are higher than the real source of the water, which is out in the country miles away, and as water will not run up hill, it is necessary to keep the city’s daily supply in some place that is higher than the highest faucet in the city, so that it will force its way into and fill to the very end all of the large pipes in the streets and the small pipes which go into the houses, so that the water will come out just as soon as you turn the faucet.

Then he takes you over to a large building near the reservoir which you have always called the water works, but never knew exactly what it was for. He takes you into a large room where there is a lot of nice-looking machinery working away steadily but quietly, and tells you that these are the great pumps which lift the water from the great pipes which bring it from far away in the country, into the reservoir we have just seen, from which the water runs into and fills all of the pipes into the city.

He also tells you that in some cities it is impossible to find a place to build a reservoir which is higher than the highest places in the city. In such places, the pumps in the water works pump the water direct into the city water pipes and force the water to the very end of all the pipes and keep it there under pressure all the time.

From the pumping station he takes you down stairs in the water works and shows you the huge pipe which brings the water to the water works from the country. It is quite the largest pipe you ever saw. You see it is not really an iron pipe, but built of concrete, which is quite as good. You will be surprised to have our friend, the water-works man, tell you that three average-sized men could stand up on each other’s shoulders inside the great pipe.

[Illustration: HOW THE BIG PIPES ARE LAID THROUGH THE COUNTRY

OLIVE BRIDGE DAM; ESOPUS CREEK FLOWING THROUGH TEMPORARY TUNNEL.]

[Illustration: PLACING THE 9¹⁄₂ FOOT STEEL PIPES.]

[Illustration: A HUGE UNDERGROUND RIVER

The water is conducted from Ashokan reservoir as a huge, underground, artificial river. The aqueduct is ninety-two miles in length from Ashokan to the northern city line, and it should be explained that it is built on a gentle grade, and that the water flows through this at a slow and fairly constant speed. The aqueduct contains four distinct types: the cut-and-cover, the grade tunnel, the pressure tunnel, and the steel-pipe siphon. The cut-and-cover type, which is used on fifty-five miles of the aqueduct, is of a horseshoe shape and measures 17 feet high by 17 feet 6 inches wide, inside measurements. It is built of concrete, and on completion it is covered in with an earth embankment. This type is used wherever the nature of the ground and the elevation allow. Where the aqueduct intersects hills or mountains, it is driven through them in tunnel at the standard grade. There are twenty-four of these tunnels, aggregating fourteen miles in length. They are horseshoe in shape, 17 feet high by 16 feet 4 inches wide, and they are lined with concrete. When the line of the aqueduct encountered deep and broad valleys, they were crossed by two methods: if suitable rock were present, circular tunnels were driven deep within this rock and lined with concrete. There are seven of these pressure tunnels of a total length of seventeen miles. Their internal diameter is 14 feet, and at each end of each tunnel a vertical shaft connects the tunnel with the grade tunnel above. If the bottom of the valley did not offer suitable rock for a rock tunnel, or if there were other prohibitive reasons, steel siphons were used. These are 9 feet and 11 feet in diameter. They are lined with two inches of cement mortar and are imbedded in concrete and covered with an earth embankment. There are fourteen of these pipe siphons of a total length of six miles. At present one pipe suffices to carry the water. Ultimately three will be required for each siphon.]

Our water-works man sees how earnest you are in seeing just where the water comes from, so he proposes that we go find out. We go outside and there is an automobile all ready to go and we jump in and the machine starts off along quite one of the nicest roads you were ever on. Soon you exclaim, “Why, this is the aqueduct road,” and so it is. The great pipe through which the water comes to the city is an aqueduct and they have built the road right over the place where the aqueduct runs. Away we go as fast as the car can carry us, sometimes ten, or twenty or perhaps fifty miles, according to what city you are in. The city goes as far as it must to find a supply of pure water and plenty of it and spends millions upon millions of dollars to make its supply of water good and certain. Occasionally we come to a little stone house along the way where we can go down and see the sides of the great stone pipe. After a while, however, we find our aqueduct road comes to an abrupt stop before another great stone wall. It is the great dam which has been built out there in the country to form one end of a great tank that catches and holds the waters from the creeks and rivers that flow into it. Usually the dam is built up right across a river. They simply build the dam strong enough to stop the river from going any further. Then, of course, the water piles up on the other side of the dam and occasionally this tank, which is simply another huge reservoir, gets so full that the water flows over. It does not really overflow the top of the dam, because underneath the top the engineers have left openings here and there for the water to get through. If it were not for these loopholes, so to speak, the great wall of water within the reservoir, piled against the dam, would break down the wall no matter how well built, by the great pressure it exerts.

[Illustration: THROUGH THIS CHAMBER THE FLOW OF WATER TO THE AQUEDUCT IS REGULATED.]

~THE REAL SOURCE OF THE WATER~

We are now near to the real source of the water. We take a trip around the top of the great reservoir. Around at the other end we find what looks like a river, excepting that there isn’t any current to speak of. It is a river, but a much deeper one than it would have been but for the dam which has been built across it, and originally its surface was quite far down in a valley. Sometimes man makes his water dam at one end of a lake, which has been formed by streams flowing into a valley which has no opening for the water to run out of. In these cases the lake will be high up in the hills and man simply builds his dam at one end, lets the end of his aqueduct into the bottom of the lake and the water flows. In other cases he picks out a valley where there is no lake at all, builds his dam and then drains the water which he finds in small lakes higher up in the hills into the one big valley and makes a very large lake. But the water in the lakes comes originally from the creeks, rivers or springs which run into it, and so we will follow our original river back into the hills. Here and there along its course we find a little stream flowing into our river and, as we go up higher and higher into the hills, we find our river getting smaller and smaller. Now it is only a creek and, if we go far enough, we find its source but the tiniest kind of a tinkling brook with the water dripping almost noiselessly between the rocks as it makes its path down the side of the hill. There is the source of the water in the glass you have just enjoyed.

[Illustration: DIGGING A HOLE UNDER A RIVER

DIAMOND DRILL BORING A HORIZONTAL HOLE 1100 FEET BELOW THE HUDSON RIVER.]

[Illustration: HUDSON RIVER SIPHON, 1100 FEET BELOW THE RIVER.

Of the many siphons constructed, by far the most interesting and difficult is that which has been completed beneath the Hudson River. The preliminary borings made from scows in the river showed that great depths would have to be reached before rock sufficiently solid and free from seams was encountered to withstand the enormous hydraulic pressure of the water in the tunnel. After failing to reach rock by the scow drills, two series of inclined borings were made from each shore, one pair intercepting at about 900 feet depth and the other at about 1500 feet. Both showed satisfactory rock, and accordingly a shaft was sunk on each shore, to a depth of approximately 1100 feet, and then a horizontal tunnel was driven connecting the two. It is of interest to note that because of the enormous head, which must be measured from the flow line far above the river surface, the pressure in the horizontal tunnel reaches over forty tons per square foot.]

[Illustration: THE HIGHEST BUILDING IN THE WORLD UPSIDE DOWN

SHAFT 752′-0 DEEP

WOOLWORTH BUILDING 750′ 0″ HIGH

This picture shows the depth to which the pipes which carry the water through the city must sometimes be sunk in order that it will be certain to remain in place. To illustrate this in connection with the depth of the water tunnel in one place in the city of New York, our artist has taken the liberty of turning the Woolworth Building upside down. Even this building, which is the tallest business building in the world, and is 792 feet high, would not penetrate the water tunnel, at the point shown, which is at the Clinton Street shaft at the west bank of the East River.]

What is Carbonic Acid?

It was formerly called fixed air, and is a gaseous compound of carbon and oxygen. It is procured by the processes of combustion and respiration, and hence is always present in the air, though in minute quantity. Plants live upon it and absorb it into their tissues; they abstract and assimilate its carbon, and return its oxygen to the atmosphere in a pure condition. It is also present in spring water, and often in quantities, so that it sparkles and effervesces; it is also produced during the processes of putrefaction, fermentation, and slow decay of animal and vegetable substances in presence of air. It is largely employed by the manufacturers of aerated bread and aerated waters. Under a pressure of about 600 pounds it liquefies, and when allowed to escape through a small jet it rapidly evaporates and causes intense cold, so much so as to become frozen. It does not support burning. The gas derived from it, carbon dioxide, is invisible, and is heavier than air by one half, and has a pungent odor and slightly acid taste. In a pure state the gas cannot be respired, as it supports neither respiration nor combustion. When the portion in the atmosphere is increased to a considerable extent, as happens sometimes, it endangers life. The familiar “rising” of bread is brought about by carbonic acid gas escaping through and permeating the dough, making it light and porous. In this form it is known as yeast or as baking powder. We see its uses also in the chemical fire-engine.

In some parts of the world large quantities of carbonic acid gas are constantly issuing from openings of the earth’s surface. Two such places are the famous Poison Valley of Java, and the Grotto del Cane, near Naples, in Italy. The former is a small valley about a half a mile around and about thirty-five feet deep, in which the air is so loaded with carbonic acid gas that animals entering it are killed in a few minutes. Even birds that fly over the valley are overcome if they do not rise high above it. The Grotto del Cane, or Grotto of the Dog, is a small cavern in the crater of a volcano. A stream of carbonic acid gas flows constantly into the grotto, but the level of the gas does not reach the height of a man’s mouth. When the same air is breathed over and over again, the quantity of carbonic acid in it is increased so much, that it may become as deadly as the air in the Poison Valley.

Two other gases that may generally be found in air are ozone and ammonia. The first is merely a form of oxygen that is produced by the passage of lightning through the air. After severe thunderstorms, it is said to be present, sometimes, in sufficient proportion to give to the air a slightly pungent odor. It is more active chemically than is the ordinary form of oxygen, and consequently has a stimulating effect upon animals.

Ammonia, or hartshorn, as it is sometimes called, from the fact that it was formerly obtained by distilling the horns of harts, or deer, is almost always present in the air in small quantities. It is produced chiefly by the decay of animal and vegetable matter, especially the former. Though present in the air in very small quantities, it is of much value to the plant world, because it contains nitrogen in a form in which it can be readily absorbed by plants. All plants contain some nitrogen, which is essential to their growth, but the greater part of the nitrogen in the air is not in such form that it can be absorbed by them. They must obtain their supply from the soil, which usually contains some nitrogen in a form that may be taken up by plants, and from the ammonia in the air. The latter is not taken directly out of the air by the plants, but the rains falling through the air absorb the ammonia and carry it to the soil, from which it is taken up into the plants by their roots.

~VARIOUS GASES FOUND IN AIR~

Besides the gases that have been mentioned, there is present in the air, at all times, a small quantity of water-vapor, which is, in many ways as important to mankind as is the oxygen itself. The quantity of water in the air is not always the same. As a rule, the quantity is greater in warm air than in cold, and is less over land than over water. Frequently the air feels damp in cold weather, and dry in hot weather, and it is natural to suppose that there is more vapor in the air on the damp day than on the dry one. This, however, is not always true. There is usually more moisture in the air on a warm summer day than on a cold day in winter, though the winter day may seem much more moist. You will be able to understand why this is so by comparing the air to a sponge. If we fill a sponge with water, and squeeze it gently, a little water will be forced out of it. If we then remove the pressure on the sponge. When the air cools, will appear dry on the surface, but there will still be water in it, and on being squeezed harder than before it will again become moist on the surface and more water will be forced out of it. Now cold has an effect upon moisture-laden air very much like that of pressure on the sponge. When the air cools, some of the moisture is forced out of it, and the air seems damp. When it warms again, the air seems dry, though there is still water-vapor in it. It seems dry because it can absorb more water-vapor, just as the sponge seems dry after you cease to squeeze it, though it still contains water. From this we see that the air does not always seem moist when there is much water-vapor in it, nor dry when there is only a little. It feels moist when there is as much water-vapor present as it can hold, and dry when it can held more than it already has. And we also see that in hot weather the air can hold much more moisture than it can in cold weather, so that whether the air feels dry or moist, there is generally much more water-vapor in it in hot weather than in cold.

It is easy to see that, over water, the air naturally takes up more moisture than over land, because there is so much more water there to be transformed into vapor. Over the surface of seas, lakes and rivers, water is continually being converted into vapor by the process of evaporation, and this vapor is absorbed by the air.

Let us now consider the solid particles floating in the air, the dust that is seen dancing in the path of a sunbeam. Whenever we examine the air, these small particles are found, even on the tops of mountains, and at points so high above the earth that they have been reached only by balloons. Of course, there is very much less dust high above the earth than near the surface, where the winds are constantly stirring up the loose soil, and throwing into the air small particles of every kind. In cities, where factory chimneys are continually pouring out clouds of smoke, and the people and vehicles are constantly disturbing the dust of the streets, the air always contains more dust than does the air of the country.

In order that we may breathe air, the oxygen in it has been mixed with four times as much nitrogen and argon, which must be inhaled with the oxygen, though they have no more effect on the body than the water you take with a strong medicine to weaken it. The oxygen, however, has a very important effect upon the body, and if we compare the air we exhale with that we inhale we find considerably less oxygen in the former than in the latter. In place of the oxygen, the air has received carbonic acid gas. It may seem very strange to say that there is burning going on in the body, but that is very nearly what takes place. The chief difference from coal-burning is that in the body the process goes on so slowly that it does not make the body very hot; but when we set fire to coal, the process is much more rapid, and a large amount of heat is produced in a short time, so that the coal becomes very hot. The products of breathing and of coal-burning are the same, carbonic acid gas being the chief one. When coal is burned it disappears, together with some of the oxygen of the air, and in their stead we have carbonic acid gas. When a breath is taken some of the material of the body disappears, as does some of the oxygen of the air, and in place of them carbonic acid gas is found. If we could weigh the coal burned and the oxygen that disappears in the burning of it, and could then weigh the carbonic acid gas that is produced in the burning, we should find that the latter weighs just as much as the coal and the oxygen together. So, too, if we could weigh the oxygen that disappears from the air we breathe, and also find the weight of the material taken from our bodies by breathing, we should find that the two together weigh just as much as the carbonic acid gas given off in our breath. In neither case is anything absolutely destroyed; the substances resulting from the change weigh just as much as those that took part in it.

Having learned that a quantity of oxygen disappears every time we take a breath, every time we build a fire, it would seem that in the thousands of years during which men and animals have been living on the earth, all the oxygen would have been exhausted and nothing left in its place but carbonic acid gas. That, however, is impossible, as the carbonic acid gas is used up almost as fast as it is produced and the oxygen is returned to the air in its stead.

~HOW PLANTS EAT CARBONIC ACID~

All trees and plants, from the great redwood trees of California to the smallest flowers that dot the fields, need carbonic acid gas to keep them alive and to make them grow. Their leaves have the power when the sun shines on them to take up carbonic acid from the air and to return oxygen in exchange. In this way you see that the balance is kept just as it should be. The oxygen needed by animals of all kinds is furnished by the plants, and the carbonic acid required by plants is thrown off in the breath of animals.

Is It a Fact that the Sun Revolves On Its Axis?

It is a proved fact that the sun revolves on its axis. All parts of its surface, however, do not rotate with the same velocity. The rotation of the sun differs from that of the earth in this respect.

This constitutes the visible proof that the physical state of the sun is different from the earth’s, although they are composed of similar chemical elements.

The earth, being covered with a solid crust, and being also, as recent investigation demonstrates, as rigid as steel throughout its entire globe, rotates with one and the same angular velocity from the equator to the poles.

If you stood on the earth’s equator you would be carried by its daily rotation round a circle about 25,000 miles in circumference. If you stood within a yard of the North or South Pole you would be carried, by the same motion, round a circle not quite 19 feet in circumference. And yet it would require precisely the same time, viz., twenty-four hours, to describe the 19-foot circle as the 25,000-mile one.

What Is the Most Usefully Valuable Metal?